Interface detector for blood processing system

ABSTRACT

Blood separation systems and methods are provided for controlling the interface between separated blood components. The system includes a centrifuge assembly having a light-transmissive portion, a light reflector, and a fluid processing region therebetween. An optical sensor system emits a scanning light beam along a path toward the light-transmissive portion, which transmits at least a portion of the scanning light beam to the fluid processing region and the light reflector. The light reflector reflects at least a portion of the scanning light beam toward the optical sensor system along a path substantially coaxial to the path of the scanning light beam from the optical sensor system toward the light-transmissive portion of the centrifuge assembly. The scanning light beam may be a white light beam or narrow spectrum beam. The reflected beam may be directed through the optical sensor system via optical fibers.

RELATED APPLICATION

This application claims the benefit of and priority of U.S. ProvisionalPatent Application Ser. No. 61/696,343, filed Sep. 4, 2012, the contentsof which are incorporated by reference herein.

DESCRIPTION Technical Field

The disclosure relates to blood treatment systems and methods. Moreparticularly, the disclosure relates to systems and methods foroptically detecting or monitoring characteristics of fluid (e.g., thelocation of an interface between separated blood components) within acentrifugal blood processing device.

BACKGROUND

Various blood processing systems now make it possible to collectparticular blood constituents, instead of whole blood, from a bloodsource. Typically, in such systems, whole blood is drawn from a bloodsource, the particular blood component or constituent is separated,removed, and collected, and the remaining blood constituents arereturned to the blood source. Removing only particular constituents isadvantageous when the blood source is a human donor, because potentiallyless time is needed for the donors body to return to pre-donationlevels, and donations can be made at more frequent intervals than whenwhole blood is collected. This increases the overall supply of bloodconstituents, such as plasma and platelets, made available for transferand/or therapeutic treatment.

Whole blood is typically separated into its constituents throughcentrifugation. This requires that the whole blood be passed through acentrifuge after it is withdrawn from, and before it is returned to, theblood source. To reduce contamination and possible infection (if theblood source is a human donor or patient), the blood is preferablyprocessed within a sealed, sterile fluid flow system during thecentrifugation process. Typical blood processing systems include adisposable, sealed, and sterile flow circuit, including a centrifugechamber portion, that is mounted in cooperation on a durable, reusableassembly containing the hardware (centrifuge, drive system, pumps, valveactuators, programmable controller, and the like) that rotates acentrifuge chamber and controls the flow through the fluid circuit.

The centrifuge rotates the centrifuge chamber of the disposable flowcircuit during processing. As the centrifuge chamber is rotated by thecentrifuge, the heavier (greater specific gravity) components of thewhole blood in the centrifuge chamber, such as red blood cells, moveradially outwardly away from the center of rotation toward the outer or“high-G” wall of the centrifuge chamber. The lighter (lower specificgravity) components, such as plasma, migrate toward the inner or “low-G”wall of the centrifuge chamber. The boundary that forms between thedenser red blood cells and the lighter plasma in the centrifuge chamberis commonly referred to as the interface. Various ones of thesecomponents can be selectively removed from the whole blood by providingappropriately located channeling structures and outlet ports in the flowcircuit. For example, in one blood separation procedure, plasma isseparated from cellular blood components and collected, with thecellular blood components and a replacement fluid being returned to theblood source. Alternatively, red blood cells may be harvested from thecentrifuge chamber and the rest of the blood constituents returned tothe donor. Other processes are also possible including, withoutlimitation, platelet collection, red blood cell exchanges, plasmaexchanges, etc. In these procedures, the efficiency of the process isoften dependent upon accurate identification and control of the positionof the interface during centrifugation.

It is known to employ an optical sensor system to monitor the flow ofblood and/or blood components through the flow circuit in the centrifugeand determine various characteristics of the flow. For example, U.S.Pat. No. 6,899,666 to Brown relates to an optical sensor system forviewing into the centrifuge chamber for detecting and controlling thelocation of an interface between separated blood components in acentrifuge. While this system functions satisfactorily, there remains anopportunity to provide optical monitoring systems with improvedinterface detection and greater robustness.

SUMMARY

There are several aspects of the present subject matter which may beembodied separately or together in the devices and systems described andclaimed below. These aspects may be employed alone or in combinationwith other aspects of the subject matter described herein, and thedescription of these aspects together is not intended to preclude theuse of these aspects separately or the claiming of such aspectsseparately or in different combinations as set forth in the claimsappended hereto.

In one aspect, a blood processing system includes a centrifuge assemblyhaving a light-transmissive portion, a light reflector, and a fluidprocessing region at least partially positioned between thelight-transmissive portion and the light reflector. The blood processingsystem also includes an optical sensor system configured to emit ascanning light beam along a path toward the light-transmissive portionof the centrifuge assembly. The light-transmissive portion of thecentrifuge is configured to transmit at least a portion of the scanninglight beam to the fluid processing region and the light reflector. Thelight reflector is configured to reflect at least a portion of thescanning light beam toward the optical sensor system along a pathsubstantially coaxial to the path of the scanning light beam from theoptical sensor system toward the light-transmissive portion of thecentrifuge assembly.

In another aspect, a method is provided for monitoring fluid within ablood processing system having a centrifuge assembly. The methodincludes separating blood in a centrifuge assembly into at least twoblood components and directing a scanning light beam along a path towardand into the centrifuge assembly so as to intersect the blood or atleast one of the blood components. At least a portion of the scanninglight beam is reflected after intersecting the blood or blood component,with the reflected light being directed along a path out of thecentrifuge assembly that is substantially coaxial to the path of thescanning light beam toward and into the centrifuge assembly. At least aportion of the reflected light is received and analyzed.

In yet another aspect, an optical sensor system is provided for use incombination with a blood processing system. The optical sensor systemincludes a light source, a light detector, and an optical fiberproviding a light path between the light source and the light detector.

In another aspect, a blood processing system includes a centrifugeassembly having a light-transmissive portion, a light reflector, and afluid processing region at least partially positioned between thelight-transmissive portion and the light reflector. The blood processingsystem also includes an optical sensor system having a light sourceconfigured to emit a source light beam, a light detector, and an opticalfiber providing a light path to the light detector. Thelight-transmissive portion of the centrifuge assembly is configured totransmit at least a portion of the source light beam to the fluidprocessing region and the light reflector. The light reflector isconfigured to reflect at least a portion of the source light beam towardthe optical sensor assembly. The optical fiber is configured to conductat least a portion of the reflected source light beam toward the lightdetector.

In yet another aspect, a method is provided for monitoring fluid withina blood processing system having a centrifuge assembly. The methodincludes separating blood in a centrifuge assembly into at least twoblood components and generating a source light beam. At least a portionof the source light beam is directed into the centrifuge assembly so asto intersect the blood or at least one of the blood components. At leasta portion of the source light beam is reflected after intersecting theblood or blood component and is then directed toward a light detectorthrough an optical fiber.

In another aspect, an optical sensor system for use in combination witha blood processing system includes a white light source.

In yet another aspect, a blood processing system includes a centrifugeassembly having a light-transmissive portion and a fluid processingregion positioned at least partially adjacent to the light-transmissiveportion. The blood processing system also includes an optical sensorsystem having a light source that emits a white light directed towardthe light-transmissive portion of the centrifuge assembly.

In another aspect, a method is provided for monitoring fluid within ablood processing system having a centrifuge assembly. The methodincludes separating blood in a centrifuge assembly into at least twoblood components and generating a source light beam comprising a whitelight. At least a portion of the source light beam is directed towardand into the centrifuge assembly so as to intersect the blood or atleast one of the blood components. At least a portion of the sourcelight beam is reflected after intersecting the blood or blood componentand at least one characteristic of the reflected source light beam isdetected.

In yet another aspect, a blood processing system includes a centrifugeassembly having a light-transmissive portion, a light reflector, and afluid processing region at least partially positioned between thelight-transmissive portion and the light reflector. The blood processingsystem also includes an optical sensor system having a light sourceconfigured to emit a source light beam and a plurality of lightdetectors. The light-transmissive portion of the centrifuge assembly isconfigured to transmit at least a portion of the source light beam tothe fluid processing region and the light reflector. The light reflectoris configured to reflect at least a portion of the source light beamtoward the optical sensor system. The plurality of light detectors areconfigured to detect at least one characteristic of the reflected sourcelight beam at different locations.

In another aspect, a method is provided for monitoring fluid within ablood processing system having a centrifuge assembly. The methodincludes separating blood in a centrifuge assembly into at least twoblood components and generating a source light beam. The source lightbeam is directed toward and into the centrifuge assembly so as tointersect the blood or at least one of the blood components. At least aportion of the source light beam is reflected after intersecting theblood or blood component and at least one characteristic of thereflected source light beam is detected at a plurality of differentlocations.

In yet another aspect, a blood processing system includes a centrifugeassembly having a rotational axis. The blood processing system alsoincludes an optical sensor system having a light source that emits asource light beam directed along a path parallel to a radius passingthrough the rotational axis of the centrifuge assembly. The path of thesource light beam is oriented so as to not pass through the rotationalaxis of the centrifuge assembly.

In another aspect, a method is provided for monitoring fluid within ablood processing system having a centrifuge assembly with a rotationalaxis. The method includes separating blood in a centrifuge assembly intoat least two blood components and generating a source light beam. Atleast a portion of the source light beam is directed along a pathparallel to a radius passing through the rotational axis of thecentrifuge assembly, but oriented so as to not pass through therotational axis of the centrifuge assembly, and into the centrifugeassembly so as to intersect the blood or at least one of the bloodcomponents. At least a portion of the source light beam is reflectedafter intersecting the blood or blood component and then at least onecharacteristic of the reflected source light beam is detected.

In yet another aspect, a blood processing system includes a centrifugeassembly having a rotational axis. The centrifuge assembly has alight-transmissive portion, a fluid processing region positionedradially inwardly of the light-transmissive portion, and a yokeincluding a first support arm configured to rotate thelight-transmissive portion and the fluid processing region about therotational axis. The blood processing system also includes an opticalsensor system configured to direct a light toward the light-transmissiveportion of the centrifuge assembly. The yoke is positioned between thelight-transmissive portion and the optical sensor system and isconfigured to allow passage of at least a portion of the light throughthe first support arm as the light is directed toward thelight-transmissive portion.

In another aspect, a blood processing system includes a centrifugeassembly having a rotational axis. The centrifuge assembly has alight-transmissive portion, a fluid processing region positionedradially inwardly of the light-transmissive portion, and a yoke. Theyoke includes a first support arm configured to rotate thelight-transmissive portion and the fluid processing region about therotational axis. An optical fiber bundle extends between first andsecond ends and is associated with the support arm of the yoke. Theblood processing system also includes an optical sensor systemconfigured to direct a light toward the first end of the optical fiberbundle. The second end of the optical fiber bundle directs the lighttoward the light-transmissive portion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation view, with portions broken away and insection, of one example of a blood separation system employing aspectsof the present invention, with a centrifuge bowl and spool of the systembeing shown in their operating position;

FIG. 2 is a side elevation view, with portions broken away and insection, of the system shown in FIG. 1, with the bowl and spool shown inan upright position for receiving a blood separation chamber;

FIG. 3 is a top perspective view of the spool of the centrifuge shown inFIG. 2 in its upright position and carrying the blood separationchamber;

FIG. 4 is a plan view of the blood separation chamber shown in FIG. 3,out of association with the spool;

FIG. 5 is an enlarged perspective view of an interface ramp carried bythe centrifuge in association with the blood separation chamber, showingthe centrifugally separated red blood cell layer, plasma layer, andinterface within the chamber when in a desired location on the ramp;

FIG. 6 is an enlarged perspective view of the interface ramp shown inFIG. 5, showing the red blood cell layer and interface at an undesiredhigh location on the ramp;

FIG. 7 is an enlarged perspective view of the interface ramp shown inFIG. 5, showing the red blood cell layer and interface at an undesiredlow location on the ramp;

FIG. 8 is a front perspective view of the bowl of the centrifuge of FIG.1 and an optical sensor system or assembly, inverted from the usualoperating position for clarity, which may form a part of an interfacecontroller to view the interface ramp during rotation of the bowl;

FIG. 9 is a rear perspective view of the bowl and optical sensor systemor assembly of FIG. 8;

FIG. 10 is a cross-sectional view of the optical sensor system orassembly of FIG. 8;

FIG. 11 is a perspective view of selected internal components of theoptical sensor system or assembly of FIG. 8, with a housing or case ofthe optical sensor assembly omitted for illustrative purposes;

FIG. 11A is a perspective view of an alternative embodiment of theselected internal components of the optical sensor system of FIG. 11;

FIG. 11B is a perspective view of another alternative embodiment of theselected internal components of the optical sensor system of FIG. 11;

FIG. 12 is a top plan view of the bowl and optical sensor system orassembly of FIG. 8, with a housing or case of the optical sensor systemomitted for illustrative purposes;

FIGS. 13 and 14 illustrate a light beam from the optical sensor systemof FIG. 8 passing through the interface ramp of the centrifuge bowl anda centrifuge container or other fluid passage containing blood or bloodcomponents;

FIG. 15 is a schematic view of the interconnectivity of selectedelectronic components of the optical sensor system of FIG. 8;

FIG. 16 is a schematic view of the interface controller, incorporatingthe optical sensor system of FIG. 8;

FIG. 17 is a perspective view of an alternative centrifuge yoke for usewith optical sensor systems according to the present disclosure;

FIGS. 18 and 19 are cross-sectional views of the centrifuge and yoke ofFIG. 17, showing sight lines into the centrifuge in different centrifugepositions;

FIG. 20 is a partial cross-sectional view of another embodiment of analternative centrifuge yoke for use with optical sensor systemsaccording to the present disclosure;

FIG. 21 is a cross-sectional detail view of a lower end of an opticalfiber bundle associated with the yoke of FIG. 20;

FIG. 22 is an end view of the lower end of the optical fiber bundleassociated with the yoke of FIG. 20;

FIG. 23 is an end view of the upper end of the optical fiber bundleassociated with the yoke of FIG. 20; and

FIG. 23A is an end view of an alternative embodiment of the upper end ofthe optical fiber bundle associated with the yoke of FIG. 20.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

The embodiments disclosed herein are for the purpose of providing adescription of the present subject matter, and it is understood that thesubject matter may be embodied in various other forms and combinationsnot shown in detail. Therefore, specific embodiments and featuresdisclosed herein are not to be interpreted as limiting the subjectmatter as defined in the accompanying claims.

FIGS. 1 and 2 show a centrifugal blood processing system 10 with aninterface controller 12 (FIG. 16) having improved interface detectioncapabilities. The illustrated system 10 shares many centrifuge designaspects with a system currently marketed as the AMICUS® separator byFenwal, Inc. of Lake Zurich, Ill., as described in greater detail inU.S. Pat. No. 5,868,696, which is hereby incorporated herein byreference. The system 10 can be used for processing various fluids, butis particularly well suited for processing whole blood, bloodcomponents, or other suspensions of biological cellular materials.

While interface control and optical detection principles will bedescribed herein with reference to one particular system 10 andcentrifuge assembly 14, it should be understood that these principlesmay be employed with other fluid processing systems (e.g., othercentrifugal blood separation systems and centrifuges) without departingfrom the scope of the present disclosure.

A. The Centrifuge Assembly

The system 10 includes a centrifuge assembly 14 used to centrifugallyseparate blood components. The system 10 may be programmed to separateblood into a variety of components (e.g., platelet concentrate,platelet-rich plasma, and red cells). It may be used for plateletcollection, therapeutic plasma exchange, red cell exchange, red cell orplasma collection, or other blood processing applications. Forillustrative purposes only, a platelet collection procedure and atherapeutic plasma exchange procedure will be described herein. However,the principles described and claimed herein may be employed with otherblood separation procedures without departing from the scope of thepresent disclosure.

The illustrated centrifuge assembly 14 shares certain design aspectswith the one shown in U.S. Pat. No. 5,316,667 to Brown et al., which isincorporated herein by reference. The illustrated centrifuge assembly,which is shown for purposes of illustration and not limitation,comprises a bowl 16 and a spool 18. In one embodiment, the bowl 16 andspool 18 are pivoted on a yoke 20 between an operating position (FIG. 1)and a loading/unloading position (FIG. 2). Other methods of accessingthe bowl 16 and the spool 18 may also be employed without departing fromthe scope of the present disclosure. The present subject matter may beused with centrifuges that do not employ such a spool and bowl, such asmolded centrifuge chambers, centrifuge bowls with pre-formed processingchamber slots, or other designs.

When in the loading/unloading position, the spool 18 can be opened bymovement at least partially out of the bowl 16, as FIG. 2 shows. In thisposition, the operator wraps a flexible blood separation chamber 22 (seeFIG. 3) about the spool 18. Closure of the spool 18 and bowl 16 enclosesthe chamber 22 between the inner surface of the bowl 16 and the outersurface of the spool 18 (which collectively define the fluid processingregion in which the chamber 22 is received) for processing. When closed,the spool 18 and bowl 16 are pivoted into the operating position of FIG.1 for rotation about a rotational axis.

B. The Blood Separation Chamber

The blood separation chamber 22 can be variously constructed. FIG. 4shows a representative embodiment.

The chamber 22 shown in FIG. 4 allows for either single- or multi-stageprocessing. When used for multi-stage processing of whole blood, a firststage 24 separates whole blood into first and second components.Depending on the nature of the separation procedure, one of thecomponents may be transferred into a second stage 26 for furtherprocessing.

As FIGS. 3 and 4 best show, there are three ports 28, 30, and 32associated with the first stage 24. Depending on the particular bloodprocessing procedure, the ports may have different functionality but, inan exemplary procedure, the port identified at 32 may be used forconveying blood (which may include anticoagulant) from a blood source ordonor into the first stage 24. During such a procedure, the other twoports 28 and 30 may serve as outlet ports for separated blood componentsexiting the first stage 24. For example, the first outlet port 30 mayconvey a low density blood component from the first stage 24, while thesecond outlet port 28 may convey a high density blood component from thefirst stage 24.

In a method of carrying out single-stage processing, one of theseparated components is returned to the donor, while the other isremoved from the first stage 24 and stored. For example, when carryingout a therapeutic plasma exchange procedure, whole blood in the firststage 24 is separated into cellular components (i.e., a high density redblood cell component) and substantially cell-free plasma (i.e., a lowdensity component). The plasma is removed from the first stage 24 viathe first outlet port 30 for collection and storage, while the cellularcomponents are removed from the first stage 24 via the second outletport 28 and returned to the donor or patient. Alternatively, rather thancollecting and storing the plasma, it may instead be discarded afterseparation or treated by a secondary device and returned to the donor orpatient.

If multi-stage processing is required, for example in a plateletcollection procedure, one of the components (platelet-rich plasma) willbe transferred from the first stage 24 to the second stage 26 via a port34 associated with the second stage 26. The component transferred to thesecond stage 26 is further fractionated into sub-components such asplasma and platelet concentrate, with one of the sub-components (plasmain one embodiment) being removed from the second stage 26 via an outletport 36 and the other sub-component (platelet concentrate in oneembodiment) remaining in the second stage 26. In the illustratedembodiment, the ports 28, 30, 32, 34, and 36 are arranged side-by-sidealong the top transverse edge of the chamber 22.

While the same ports 28, 30, and 32 of the first stage 24 are used as inthe above-described therapeutic plasma exchange procedure, the ports 28and 32 may have different functionality in a multi-stage separationprocedure. In the method of multi-stage operation for plateletcollection, blood enters the first stage 24 via the port 28 and isseparated into red blood cells (i.e., the high density blood component)and platelet-rich plasma (i.e., the low density blood component). Thered blood cells are returned to the donor (via the port 32), while theplatelet-rich plasma is conveyed out of the first stage 24 (via thefirst outlet port 30) and into the second stage 26 (via the inlet port34). In the second stage 26, the platelet-rich plasma is separated intoplatelet-poor plasma and platelet concentrate. The platelet-poor plasmais removed from the second stage 26 (via the outlet port 36), leavingplatelet concentrate in the second stage 26 for eventual resuspensionand transfer to one or more storage containers.

As best shown in FIG. 3, a tubing umbilicus 38 is attached to the ports28, 30, 32, 34, and 36. The umbilicus 38 interconnects the rotatingfirst and second stages 24 and 26 with each other and with pumps andother stationary components located outside the rotating components ofthe centrifuge assembly 14 (see FIGS. 1 and 2). As FIG. 1 shows, anon-rotating (zero omega) holder 40 holds the upper portion of theumbilicus 38 in a non-rotating position above the spool 18 and bowl 16.A holder 42 on the yoke 20 rotates the mid-portion of the umbilicus 38at a first (one omega) speed about the suspended spool 18 and bowl 16.Another holder 44 (FIGS. 2 and 3) mounts the lower end of the umbilicus38 to the centrifuge assembly 14. The inherent strength of the umbilicus38 causes the centrifuge assembly 14 to rotate at a second speed twicethe one omega speed (the two omega speed). This known relative rotationof the umbilicus 38 keeps it from accumulating twisting, in this wayavoiding the need for rotating seals. In an alternative embodiment,rather than the holder 42 rotating the umbilicus 38 to turn thecentrifuge assembly 14, a gear system may be employed to rotate theumbilicus 38 and/or the centrifuge assembly 14 separately. It should benoted that the present subject matter can also be employed indirect-drive centrifuge assemblies (i.e., systems that rely on a geartrain to rotate the centrifuge) and centrifuge assemblies using rotatingseals, and is not limited to use in a seal-less centrifuge system.

As FIG. 4 shows, a first interior seal 46 is located between the lowdensity outlet port 30 and the high density outlet port 28. A secondinterior seal 48 is located between the high density outlet port 28 andthe blood inlet port 32. The interior seals 46 and 48 form a fluidpassage 50 (an inlet for whole blood in an exemplary platelet collectionprocedure or an outlet for high density blood components in an exemplarytherapeutic plasma exchange procedure) and a low density collectionregion 52 in the first stage 24. The second seal 48 also forms a fluidpassage 54 (an outlet for high density blood components in an exemplaryplatelet collection procedure or a blood inlet in an exemplarytherapeutic plasma exchange procedure) in the first stage 24.

In a platelet collection procedure, the fluid passage 50 channels bloodinto the first stage 24, where it separates into an optically denselayer 56 (FIG. 5), which forms as larger and/or heavier blood particlesmove under the influence of centrifugal force toward the high-G (outer)wall 62. The optically dense layer 56 will include red blood cells (and,hence, may be referred to herein as the “RBC layer”) but, depending onthe speed at which the assembly 14 is rotated, other cellular components(e.g., larger white blood cells) may also be present in the RBC layer56.

Rather than flowing blood into the first stage 24 by the fluid passage50 (as in a platelet collection procedure), blood enters the first stage24 by the fluid passage 54 in a therapeutic plasma exchange procedure,but is still separated into an RBC layer 56. In comparison to a plateletcollection procedure, the centrifuge assembly 14 rotates at a higherspeed during a therapeutic plasma exchange procedure, creating astronger separation field in the first stage 24. As a result of thestronger separation field, additional cellular components, namely whiteblood cells and platelets, will be present in a greater quantity in theRBC layer 56.

In both cases, the movement of the component(s) of the RBC layer 56displaces less dense blood components radially toward the low-G (inner)wall 64, forming a second, less optically dense layer 58. In anexemplary platelet collection procedure, the less optically dense layer58 includes platelet-rich plasma (and, hence, will be referred to hereinas the “plasma layer”). In an exemplary therapeutic plasma exchangeprocedure, the less optically dense layer 58 includes substantiallycell-free plasma. However, depending on the speed at which thecentrifuge assembly 14 is rotated and the length of time that the bloodis resident in the centrifuge assembly, other components (e.g., smallerwhite blood cells) may also be present in the plasma layer 58.

The transition between the RBC layer 56 and the plasma layer 56 isgenerally referred to as the interface 60 (FIG. 5). Platelets and whiteblood cells (which have a density greater than plasma and usually lessthan red blood cells) typically occupy this transition region, althoughthat also varies with centrifuge speed and residence time, as is wellknown in the technical field.

The location of the interface 60 within the chamber 22 can dynamicallyshift during blood processing, as FIGS. 6 and 7 show. If the location ofthe interface 60 is too high (that is, if it is too close to the low-Gwall 64 and the removal port 30, as FIG. 6 shows), cellular componentscan spill over and into the low density collection region 52,potentially adversely affecting the quality of the low densitycomponents (typically plasma). On the other hand, if the location of theinterface 60 is too low (that is, if it resides too far away from thelow-G wall 64, as FIG. 7 shows), the collection efficiency of the system10 may be impaired.

In the illustrated embodiment, as FIG. 5 shows, a ramp 66 extends fromthe high-G wall 62 of the bowl 16 at an angle “A” across the low densitycollection region 52. The angle “A,” measured with respect to the axisof the first outlet port 30 is about 25° in one embodiment. FIG. 5 showsthe orientation of the ramp 66 when viewed from the low-G wall 64 of thespool 18. FIG. 4 shows, in phantom lines, the orientation of the ramp 66when viewed from the high-G wall 62 of the bowl 16.

Further details of the angled relationship of the ramp 66 and the firstoutlet port 30 can be found in U.S. Pat. No. 5,632,893 to Brown et al.,which is incorporated herein by reference. The ramp 66 shown in FIGS.5-7 may be considered a simplified or representational version of anactual ramp that would be used in practice. For example, FIGS. 8-9 and13-14 illustrate a particular ramp configuration that may beparticularly advantageous for imaging and interface-detection purposes,as will be described in greater detail below. However, the ramp 66 maybe variously configured without departing from the scope of the presentdisclosure.

The ramp 66 forms a tapered wedge that restricts the flow of fluidtoward the first outlet port 30. The top edge of the ramp 66 extends toform a constricted passage 68 along the low-G wall 64. The plasma layer58 must flow through the constricted passage 68 to reach the firstoutlet port 30.

As FIG. 5 shows, the ramp 66 makes the interface 60 between the RBClayer 56 and the plasma layer 58 more discernible for detection,displaying the RBC layer 56, plasma layer 58, and interface 60 forviewing through a light-transmissive portion of the high-G wall 62 ofthe chamber 22, as will be described in greater detail below.

Further details of the separation chamber 22 and its operation may befound in U.S. Pat. No. 5,316,667, which is incorporated by reference.

C. The Interface Controller

In one embodiment, the interface controller 12 (FIG. 16) includes anoptical sensor system or assembly 70 (see FIGS. 8-12) positioned at alocation outside of the centrifuge assembly 14. The optical sensorsystem 70 is oriented to detect the location of the interface 60 the RBClayer 56 and the plasma layer 58 on the ramp 66. If the interface 60detected by the optical sensor system 70 is at an improper location(e.g., in the locations of FIG. 6 or 7), the interface controller 12 isfunctional to correct the location of the interface 60, as will bedescribed in greater detail herein.

Referring to FIGS. 8-12, the optical sensor system 70 is secured to afixture or wall 74 of the system 10. The wall 74 includes an opening 76(FIG. 9) through which light from the optical sensor system 70 may bedirected toward and into the centrifuge assembly 14 via alight-transmissive portion thereof. In the illustrated embodiment, theramp 66 is translucent and comprises the light-transmissive portion ofthe centrifuge bowl 16, such that light from the optical sensor system70 passes through the ramp 66 (FIGS. 13 and 14) to intersect theseparated blood components thereon to determine the location of theinterface 60, as will be described in greater detail herein.

The optical sensor system 70 includes a variety of components, some ofwhich are contained within a housing or case 78. Among the componentsmounted within the housing 78 is at least one light source 80 (FIGS.10-12), which emits a source beam 82 of light. The optical sensor system70 may include one or more components (e.g., the achromatic prism pairs84 and aperture stop 86 of FIGS. 10-12) configured to condition and/orfocus the source beam 82 that exits the light source 80. For example, ifprovided, an achromatic prism pair 84 provides a color correctionfunction by directing two color wavelengths (e.g., blue and red) along adesired path or angle, while an aperture stop 86 controls and limits theamount of light from the light source 80 allowed to pass further throughthe optical sensor system 70. It should be understood that, depending onthe nature of the light source 80, selected components (e.g., theachromatic prism pairs 84) may be omitted from the optical sensor system70. Similarly, additional components may also be incorporated into theoptical sensor system 70 without departing from the scope of the presentdisclosure.

In the illustrated embodiment, the light source 80 comprises alight-emitting diode which emits a source light beam 82 or a pluralityof light-emitting diodes that combine to emit a source light beam 82.The light source 80 may emit a single- or multiple-wavelength sourcelight beam 82, but in a preferred embodiment, comprises a white lightsource that is configured to emit a multi-wavelength, white source lightbeam 82. If provided as a white light source, the light source 80 maycomprise one or more true white lights (e.g., incandescent or filamentlights or light-emitting diodes) or a plurality of differently coloredlight sources (e.g., red, green, and blue light-emitting diodes arrangedon a common die) that combine to simulate or approximate a white light.In one embodiment, the light source 80 is of the type which emits awhite source light beam 82 exhibiting a relatively high spectral powerdistribution in the red and blue wavelength spectra, such as a warmwhite LUXEON® light-emitting diode of Philips Lumileds Lighting Companyof San Jose, Calif.

In other embodiments, other types of light sources and source beams maybe employed without departing from the scope of the present disclosure.For example, in another embodiment, the light source comprises one ormore non-white, narrow spectrum light sources. The nature of the narrowspectrum light sources (e.g., whether they are provided aslight-emitting diode or in some other form) and the source light beamemitted by the narrow spectrum light sources (e.g., the color of thelight, if it is within the visible spectrum) may vary and is not limitedto a particular type of light source or a particular wavelength oflight. In one exemplary embodiment, a narrow spectrum light sourcecomprises a light-emitting diode configured to emit a red source lightbeam, in which case the light source may be provided as a deep redLUXEON® light-emitting diode of Philips Lumileds Lighting Company of SanJose, Calif. Other narrow spectrum red light sources may also beemployed, as well as other narrow spectrum light sources configured toemit a beam having any other suitable wavelength. If the light source isconfigured to emit a relatively wide bandwidth source beam, it may bepreferred to also provide one or more filters configured to narrow thebandwidth of either the source beam emitted by the light source and/orthe bandwidth of a light beam returning to the optical sensor system 70after having interacted with the fluid processing region.

The optical sensor system 70 also includes a plurality of lightdetectors 88, 88 a (FIG. 15). The light detectors 88, 88 a may bevariously configured without departing from the scope of the presentdisclosure, but in one embodiment they comprise silicon PIN photodiodes,which may be particularly well-suited for use with a white or red lightsource. In the illustrated embodiment, the light detectors 88, 88 a arepositioned outside of the housing 78, and may be mounted in a separatehousing. This may be advantageous for the purpose of spacing the lightdetectors 88, 88 a and other sensitive components (e.g., analogelectronics and amplifier components) away from the drive systems thatrotate the centrifuge assembly 14. Additionally, such a configurationallows for a compact optical module design, which is relatively immuneto electrical noise and vibration while allowing for electrically immunelight transmission from the optical module to a separate electronicsmodule that can be modified and upgraded for different functionalitywithout affecting the optical module design. For example, if nototherwise provided, a separate electronics module could be modified andupgraded to include spectral splitting and analysis without modifyingthe optical module.

In embodiments having the light detectors 88, 88 a mounted outside ofthe housing 78, they may be in communication with the interior of thehousing 78 via optical fibers 90-90 c (FIGS. 8-10 and 15). In theillustrated embodiment, there are four optical fibers 90-90 c (onereferred to herein as a reference fiber 90 and the others referred toherein as scanning fibers 90 a-90 c) extending between the housing 78and four light detectors 88, 88 a connected thereto by FC/PC connectorsor the like to define a portion of the light path between the lightsource and the light detectors (FIG. 15 is simplified to show only onedetector 88 a, but in the illustrated embodiment there are a plurality,preferably three or six, of such detectors 88 a). However, in otherembodiments, there may be a different number of optical fibers and lightdetectors, at least one and preferably a plurality, such as three ormore. For example, a beam splitter may be positioned at a downstream endof an optical fiber to split a beam exiting the optical fiber into twobeams, with each beam going to a different light detector.

In the illustrated embodiment, the upstream or inlet (light-receiving)ends of the optical fibers 90-90 c are oriented at an angle to theinitial direction 92 of the source light beam 82, as shown in FIGS.10-12. In one embodiment, the upstream or inlet ends of the opticalfibers 90-90 c are positioned to receive light along a directionperpendicular to the initial direction 92 of the source light beam 82.The optical fibers 90-90 c are configured to receive at least a portionof the light emitted by the light source 80, so selected components ofthe optical sensor system 70 may be configured to direct light from thelight source 80 toward one or more of the optical fibers 90-90 c. Forexample, in the illustrated embodiment, the optical sensor system 70includes a beam splitter 94 that is configured to split the source beam82 from the light source 80 into two beams 96 (reference beam or firstsplit beam) and 98 (scanning beam or second split beam) (FIGS. 11 and12). In one embodiment, the beam splitter 94 comprises a beam splittercube which splits the source beam 82, with a first split beam 96 being areference beam that is reflected at an angle (e.g., 90° in theillustrated embodiment) toward the optical fiber 90 and a second splitbeam 98 being a scanning beam that is transmitted through the beamsplitter cube 94 and toward the centrifuge assembly 14.

The optical sensor system 70 may include one or more components (e.g.,an achromatic prism pair 84 for color correction, as shown in FIGS.10-12) configured to condition and/or focus the reference beam 96 beforeit reaches the associated optical fiber 90, but the light received bythe optical fiber 90 is essentially a direct view of the source beam 82(albeit at a fraction of its original intensity) and gives an indicationof the power level of the light source 80. For this reason, the opticalfiber 90 that receives the reference beam 96 may be referred to as thereference fiber. As such, the reference fiber 90 may be associated witha light detector 88 that forms a feedback loop with a driver 100 of thelight source 80 (FIG. 15). It may be advantageous for the light source80 to emit a source beam 82 having a substantially uniform or constantbrightness, and any fluctuations in the brightness of the source beam 82are directly reflected in the brightness of the reference beam 96 and,hence, the strength of the signal transmitted from the light detector 88to the driver 100. The driver 100 or a controller may make adjustmentsto the power delivered to the light source 80 to maintain the brightnessof the source beam 82 at a substantially uniform level. In otherembodiments, the brightness of the source beam 82 may be measured andused as an input to measure fluid characteristics (e.g., lipemia orhemolysis), apart from or in addition to the brightness beingcontrolled. It is also within the scope of the present disclosure forthe brightness to be measured to determine light output degradation overtime, either apart from or in addition to the brightness beingcontrolled. The light detector 88 may be directly associated with thedriver 100 or, as shown in FIG. 15, include one or more intermediatedevices (e.g., an interface processing module 126) that may measure orcondition or otherwise interact with the signal from the light detector88 prior to reaching the driver 100 or otherwise use the signal forother purposes.

In an alternative embodiment, the reference fiber 90 is eliminated andthe light detector 88 that is positioned downstream of the referencefiber 90 in the above-described embodiment is instead positioned withinthe housing 78. For example, FIG. 11A shows an embodiment in which thelight detector 88 is placed in substantially the same location and inthe same orientation as the reference fiber 90 in FIGS. 10 and 11. Insuch an embodiment, the light detector 88 directly receives light,rather than having light transmitted thereto by the reference fiber 90.By such a configuration, other components of the optical sensor system70 (e.g., lens 84) may also be eliminated or modified. In otherembodiments, one or more of the other optical fibers 90 a-90 c may beeliminated and replaced with a light detector that is positioned in thesame or a similar position and orientation in the housing 78.

In another alternative embodiment which omits the reference fiber 90,the light detector 88 is placed in a different location within thehousing 78 (FIG. 11B), rather than being positioned at the location ofthe reference fiber 90 in FIGS. 10 and 11. In the embodiment of FIG.11B, the light detector 88 is positioned adjacent to the light source80, which may include being positioned on the same printed circuit boardas the light source 80 (if the light source 80 is mounted on a printedcircuit board), but may include any other suitable location. By such aconfiguration, other components of the optical sensor system 70 (inaddition to the reference fiber 90) may be eliminated or modified, asappropriate.

Depending on the exact location of the light detector 88, itsorientation may vary, provided that it is oriented so as to be in atleast partial light-receiving relationship with respect to the lightsource 80. In one embodiment, the light detector 88 is oriented at anangle with respect to the general path of the source beam 82. In theillustrated embodiment, a substantially side-looking light detector 88is provided, with the light detector 88 being oriented generallyperpendicular to the path of the source beam 82. In other embodiments,the light detector 88 may be positioned elsewhere within the housing 78and oriented differently, but it has been found that a side-lookinglight detector 88 positioned adjacent to the light source 80 isparticularly advantageous in terms of monitoring and controlling thelevel of light emitted by the light source 80.

Regardless of the exact location of the optical fibers and/or lightdetectors, the scanning beam 98 is transmitted through the beam splitter94 (or other suitable light-directing member) and toward the centrifugeassembly 14. The scanning beam 98 may pass through a lens or protectivewindow 102 prior to reaching the centrifuge assembly 14. The window 102may serve a number of purposes, which may include focusing the scanningbeam 98 at the proper location of the centrifuge assembly 14 and/orprotecting the components of the optical sensor system 70 containedwithin the housing 78 from debris present within the system 10. As willbe described in greater detail herein, the scanning beam 98 passesthrough the interface ramp 66 and the fluids positioned thereon(including the interface 60) before being reflected back to the opticalsensor system 70. The reflected second split beam or reflected scanningbeam 104 passes through the window 102 and encounters the beam splitter94, which directs at least a portion of the reflected scanning beam 104at an angle to the path 92 of the scanning beam 98 (FIG. 12). The path92 of the scanning beam 98 coincides with the direction in which thereflected scanning beam 104 returns to the optical sensor system 70 (aswell as the initial direction of the source light beam 82). In theillustrated embodiment, the beam splitter 94 directs at least a portionof the reflected second scanning 104 at a 90° angle to the path 92 ofthe scanning beam 98. Hence, it will be seen that the reflected scanningbeam 104 is directed in the opposite direction of the reference beam 96by the beam splitter 94.

In one embodiment, one or more optical fibers 90 a-90 c may bepositioned to directly receive the reflected scanning beam 104 from thebeam splitter 94 (i.e., being positioned along or adjacent to the sameaxis as the reference fiber 90, but oriented on the opposite side of thebeam splitter 94 and facing the opposite direction). In anotherembodiment, such as the one illustrated in FIGS. 8-11, the opticalfiber(s) 90 a-90 c configured to receive the reflected scanning beam 104(which may be referred to as scanning fibers) are positioned generallyadjacent to the reference fiber 90. More particularly, the illustratedscanning fibers 90 a-90 c are positioned below and in the same plane asthe reference fiber 90, on the same side of the beam splitter 94 andfacing in the same direction. Such a configuration may be advantageousfor a number of reasons, such as space considerations and accessibilityof the fibers for maintenance, replacement, and/or upgrade purposes. Anoptical barrier or other shielding surface may be interposed between thereference fiber 90 and the scanning fibers 90 a-90 c to prevent thereference beam 96 from illuminating the scanning fibers 90 a-90 c or thereflected scanning beam 104 illuminating the reference fiber 90.

In the illustrated embodiment, to facilitate the fiber positioningdescribed above, a beam directing member 106 (e.g., a pair of mirrors)is employed between the beam splitter 94 and the scanning fibers 90 a-90c to direct the reflected scanning beam 104 to the scanning fibers 90a-90 c. The optical sensor system 70 may include one or more components(e.g., the achromatic prism pairs 84, direct vision prism 108, andaperture stop 86 of FIGS. 10-12) configured to condition and/or focusthe reflected scanning beam 104 prior to encountering the beam directingmember 106. A direct vision prism 108 may be particularly advantageousfor undoing any dispersion of a reflected beam having passed through theramp 66 (which may be prismatic, as described below), therebycolor-correcting the reflected beam.

As for the relative position of the optical sensor system 70 withrespect to the centrifuge assembly 14, FIG. 12 shows that the path 92 ofthe scanning beam 98 may be parallel to, but offset from, a radial lineperpendicular to and passing through the rotational axis 110 of thecentrifuge assembly 14. Hence, it can be seen that the beam emitted bythe optical sensor system 70 to analyze the blood and/or bloodcomponents in the centrifuge assembly 14 neither passes through nor isparallel to the rotational axis 110 of the centrifuge assembly 14. Thismay be advantageous depending on the configuration of the ramp 66. Forexample, FIGS. 13 and 14 are cross-sectional views of the ramp 66, whichshows it with an angled inner face 112 and an angled outer face 114,which effectively make the ramp 66 a prism. As used in reference to thefaces of the ramp 66, the term “angled” refers to the fact that theinner and outer faces of the ramp 66 are non-tangential to thesubstantially circular perimeter of the bowl 16.

In the illustrated embodiment, the inner ramp face 112 is angled atapproximately 29° (from a horizontal line, in the orientation of FIGS.13 and 14) and the outer ramp face 114 is angled at approximately 26.4°(from a horizontal line, in the orientation of FIGS. 13 and 14),resulting in an approximately 55.4° prism. To minimize ghosting (show inFIG. 14 as rays 116) and maintain focus of light through the ramp 66 inview of the material (which may be a polycarbonate material in oneembodiment) and configuration of the ramp 66 (i.e., as a prism), it hasbeen found that causing the scanning beam 98 to encounter the outer rampface 114 at an angle is advantageous. By offsetting the path 92 of thescanning beam 92 from the rotational axis 110 of the centrifuge assembly14, the ramp 66 will be at an angle to the path 92 when the scanningbeam 98 encounters the outer ramp face 114. In one embodiment, the ramp66 is approximately 10° from center (see FIG. 12) when it comes into thefield of vision of the optical sensor system 70. In other embodiments,it may be advantageous for the ramp 66 to be at a different angle oreven centered when it comes into the field of vision of the opticalsensor system 70.

As for the individual faces of the ramp 66, the inner ramp face 112 isangled to display the location of the interface 60, as described ingreater detail above with respect to FIGS. 5-7. Accordingly, it is theinner ramp face 112 that the scanning beam 98 is focused upon to detectthe location of the interface 60. The outer ramp face 114 is angled tocontribute to focusing the scanning beam 98 on the inner ramp face 112at all times that the ramp 66 is within the field of vision of theoptical sensor system 70. Depending on the configuration of the opticalsensor system 70, multiple samples or readings (of the order of onehundred, in some embodiments) can be taken each time the ramp 66 rotatesthrough the field of view of the optical sensor system 70. FIGS. 13 and14 illustrate two exemplary positions of the ramp 66 during a singlepass of the ramp 66 through the field of vision of the optical sensorsystem 70, with FIG. 13 showing a portion of the right side of the innerramp face 112 being scanned or viewed and FIG. 14 showing a portion ofthe left-center side of the inner ramp face 112 being scanned or viewed.It will be seen that, in both positions, the scanning beam 98 is focusedon the inner ramp face 112, where the interface 60 is displayed.

As shown in FIGS. 13 and 14 and noted above, at least a portion of thesource beam 82 (which takes the form of the scanning beam 98 in theillustrated embodiment) is directed toward the rotating bowl 16 to passthrough the light-transmissive portion thereof, the ramp 66, and theblood or blood component displayed thereon. In the illustratedembodiment, the bowl 16 is transparent to the light emitted by the lightsource 80 only in the region at which the interface ramp 66 isincorporated into the bowl 16 (FIGS. 8 and 12). In the illustratedembodiment, the region comprises a window or opening cut out in the bowl16, which receives at least a portion of the ramp 66. The remainder ofthe bowl 16 that passes through the path of the optical sensor system 70comprises an opaque or light absorbing material. In the illustratedembodiment, the optical sensor system 70 remains stationary duringoperation of the blood processing system 10, as the spool 18 and bowl 16rotate at a two omega speed. Thus, the optical sensor system 70 may beprovided as a continuous or an always-on system (i.e., shining light onthe centrifuge assembly 14 even when the ramp 66 is out of the field ofvision of the optical sensor system 70) or as an intermittent or gatedsystem that only emits a source beam when the ramp 66 is within thefield of vision.

The light from the source 80 passes through the ramp 66, to be focusedon the inner ramp face 112 and the fluid displayed thereon (e.g., theseparated blood components and interface 60). At least a portion of thelight (i.e., the portion not absorbed or reflected by the fluids)continues through the blood separation chamber 22 and hits the spool 18.The spool 18 may carry a light-reflective material or light reflector118 (FIGS. 13 and 14) behind the interface ramp 66 to return the lightpassing through the ramp 66, the fluid on the ramp 66, and the bloodseparation chamber 22. In the illustrated embodiment, the lightreflector 118 comprises a retroreflector configured to reflect the lightalong the same path by which it strikes the retroreflector, as shown inFIGS. 13 and 14. It may be advantageous for the path 92 of the scanningbeam 98 to coincide with the direction in which the reflected scanningbeam 104 returns to the optical sensor system 70. For example, byemploying coaxial scanning and reflected scanning beams 98 and 104, itis ensured that both beams 98 and 104 pass through the same opticalcomponents at substantially the same angles from the point where thesource beam 82 enters the beam splitter 94 to the point where thereflected scanning beam 104 exits the beam splitter 94 to be focused onthe scanning fibers 90 a-90 c. As used herein, the term “opticalcomponents” refers to the surfaces and objects through which a lightbeam passes. In the case of the scanning and reflected scanning beams 98and 104, the optical components include the walls of the bloodseparation chamber 22, the fluids contained within the blood separationchamber 22, the ramp 66, the beam splitter 94, and the window 102. Whileit is preferred to employ a retroreflector to provide substantiallycoaxial scanning and reflected scanning beams 98 and 104, it is alsowithin the scope of the present disclosure to employ a light reflector118 comprising a mirror or the like, which reflects a light at the sameangle at which the light is incident to the mirror. Light reflectorsthat reflect the scanning beam 98 at some other angle may also beemployed without departing from the scope of the present disclosure.

The light reflected by the light reflector 118 passes again through theramp 66, but in the other direction toward the optical sensor system 70as a reflected beam or reflected scanning beam 104. The reflected beam104 returned to the optical sensor system 70 is ultimately directed toone or more of the light detectors 88 a for analysis. The reflected beam104 may be directed to the light detector(s) in any suitable way withoutdeparting from the scope of the present disclosure, but in theillustrated embodiment, it is directed to a plurality of light detectors88 a via the operation of the beam splitter 94, the beam deflectingmirror 106, and the scanning fibers 90 a-90 c associated with the lightdetectors 88 a, as described above in greater detail.

The reflected beam 104 is larger than the individual scanning fibers 90a-90 c, so each scanning fiber will only receive a portion of thereflected beam 104. Accordingly, by arranging the scanning fibers indifferent configurations, different locations and portions of thereflected beam 104 may be captured and analyzed. For example, in theillustrated embodiment, three scanning fibers 90 a-90 c are arranged ina generally vertical line below the reference fiber 90 (FIG. 8), therebytaking readings of upper, lower, and central portions or locations ofthe reflected beam 104. While it is within the scope of the presentdisclosure for a single reference fiber or light detector to be used toanalyze the reflected beam 104, it may be advantageous to employ aplurality of fibers and detectors to develop a more complete picture ofthe interface location. Additionally, the effect of noise on the signalsultimately received by the light detectors may be reduced by consideringa plurality of readings from different locations, and accuracy improved.

As noted above, the ramp 66 may be oriented at an approximately 25°angle with respect to the rotational axis 110 of the centrifuge assembly14, which results in the interface 60 appearing on the inner ramp face112 as a line angled at an approximately 25° angle with respect to therotational axis 110. If the scanning fibers 90 a-90 c are arranged in avertical line (as shown in FIG. 8), they will register the presence ofthe interface 60 at different times. For example, in one embodiment, theupper end of the angled interface 60 may move into the field of visionof the optical sensor system 70 before the lower end does. In this case,at some point during a particular scanning session, the upper portion ofthe scanning beam 98 will pass through the interface 60 on the ramp 66while the central and lower portions of the scanning beam 98 will passthrough some other fluid on the ramp 66 (e.g., the RBC layer 56 or theplasma layer 58). At this point, the reflected beam 104 is returned toand received by the scanning fibers 90 a-90 c, with only the lowermostscanning fiber 90 c being positioned to receive that portion of thereflected beam 104 that has passed through the interface 60 (on accountof the illustrated beam directing member 106 inverting the image of thereflected beam 104). As the centrifuge assembly 14 continues to rotatethrough the field of vision of the optical sensor system 70, the lowerportions of the scanning beam 98 will eventually pass through theinterface 60, to be registered by the central and uppermost scanningfibers at later points in time. Accordingly, the “interface” signalstransmitted to the light detectors 88 a associated with the scanningfibers 90 a-90 c will occur at different times to reflect the fact thatthe interface 60 appears as an angled line on the ramp 66.

In an alternative embodiment, rather than positioning the scanningfibers 90 a-90 c in a vertical line, they may be oriented at an angle,such as at an approximately 25° to coincide with the angle at which theramp 66 is oriented with respect to the rotational axis 110 of thecentrifuge assembly 14. As described above, the interface 60 appears onthe ramp 66 as a line oriented at approximately the same angle as thatof the ramp 66 with respect to the rotational axis 110 of the centrifugeassembly 14. Thus, by orienting the scanning fibers 90 a-90 c along aline at the same approximate angle as the ramp 66, they will be also beoriented at approximately the same angle as the interface 60 on the ramp66. With the scanning fibers 90 a-90 c arranged at the same angle as theinterface 60, the “interface” signals transmitted to the light detectors88 a associated with the scanning fibers 90 a-90 c will occursubstantially simultaneously.

By considering the previous two examples of optical fiber orientations,it will be seen that the location of the scanning fibers 90 a-90 ceffectively determines the locations on the ramp 66 that are beingmonitored by the optical sensor system 70. Thus, while the two differentscanning fiber arrangements will detect the same location of theinterface 60 on the ramp 66, they consider different regions of the ramp66 in doing so. In one embodiment, to give the optical sensor system 70additional flexibility, the scanning fibers 90 a-90 c may be mountedtogether on an adjustable module. In the illustrated embodiment, thescanning fibers 90 a-90 c are mounted together on an adjustable module120 having a tubular collar 122 (FIG. 8) extending outside of thehousing 78, which may be grasped and rotated to simultaneously adjustthe arrangement of all of the scanning fibers 90 a-90 c. In otherembodiments, the scanning fibers may be arranged for individual, ratherthan simultaneous adjustment, such as by providing an adjustable moduleor a surface of the housing with a plurality of sockets into which thevarious scanning fibers may be selectively inserted or removed to createdifferent (e.g., non-linear) one- or two-dimensional scanning profiles.The optical sensor system 70 may be configured to have a horizontalresolution (i.e., a resolution in the plane of the centrifuge assembly14) of approximately 100 μm or better, resulting in an accuratedetermination of the location of the interface 60.

As for the light detectors 88, 88 a and their contribution todetermining and adjusting the location of the interface 60 on the ramp66, FIG. 15 shows a plurality of representative light detectors 88, 88a. The lower detector 88 is associated with the reference fiber 90, asdescribed above to form a feedback loop with the light source driver 100to control the brightness of the light source 80. The upper lightdetector 88 a of FIG. 15 is associated with one of the scanning fibers90 a-90 c. FIG. 15 only shows one such detector 88 a, but there may beone or more such detectors 88 a for each scanning fiber 90 a-90 cprovided in the optical sensor system 70. Each of these light detectors88 a receives the portion of the reflected beam 104 transmitted theretoby the associated scanning fiber 90 a-90 c. Each light detector 88 aconverts the light into a signal that may pass through one or moreamplifiers 124 (e.g., a transimpedance amplifier, a gain amplifier,and/or a buffer amplifier), if provided. The individual signalsrepresent a characteristic of the fluid (e.g., the location of itsinterface) or the nature of the fluid on the ramp 66 at the locationmonitored by the associated scanning fiber 90 a-90 c. For example, inone embodiment, as the ramp 66 comes into alignment with the opticalsensor system 70, the detector(s) 88 a will first sense light reflectedthrough the plasma layer 58 on the ramp 66. Eventually, the RBC layer 56adjacent the interface 60 on the ramp 66 will enter the optical path ofthe optical sensor system 70. The RBC layer 56 absorbs at least aportion of the light and thereby reduces the previously sensed intensityof the reflected light. The intensity of the reflected light transmittedto the detector(s) 88 a is indicative of the amount of light that is notabsorbed by the RBC layer 56 adjacent to the interface 60.

The signal(s) from the optical sensor system 70 are transmitted to aninterface processing module 126 (FIG. 16), which can determine thelocation of the interface 60 on the ramp 66 relative to the constrictedpassage 68. A more detailed discussion of the algorithms by which anexemplary interface controller receives and processes signals todetermine the location of the interface on the ramp may be found in U.S.Pat. No. 6,312,607 to Brown et al., which is incorporated herein byreference.

When the location of the interface 60 on the ramp 66 has beendetermined, the interface processing module 126 outputs that informationto an interface command element or module 128 (FIG. 16). The interfacecommand module 128 may include a comparator, which compares theinterface location output with a desired interface location to generatean error signal. The error signal may take a number of forms but, in oneembodiment, may be expressed in terms of a targeted red blood cellpercentage value (i.e., the percentage of the ramp 66 which should beoccupied by the RBC layer 56).

When the control value is expressed in terms of a targeted red bloodcell percentage value, a positive error signal indicates that the RBClayer 56 on the ramp 66 is too large (as FIG. 6 shows). The interfacecommand module 128 generates a signal to adjust an operational parameteraccordingly, such as by reducing the rate at which plasma is removedthrough a tube 130 associated with the first outlet port 30 under actionof a pump 132 (FIG. 16). The interface 60 moves away from theconstricted passage 68 toward the desired control position (as FIG. 5shows), where the error signal is zero.

A negative error signal indicates that the RBC layer 56 on the ramp 66is too small (as FIG. 7 shows). The interface command module 128generates a signal to adjust an operational parameter accordingly, suchas by increasing the rate at which plasma is removed through the firstoutlet port 30 and associated tube 130. The interface 60 moves towardthe constricted passage 68 to the desired control position (FIG. 5),where the error signal is again zero.

Besides determining the location of an interface, the optical sensorsystem 70 may determine other information about the fluid in the bloodseparation chamber 22. For example, the optical sensor system 70 may beconfigured to detect and read notations (e.g., bar codes) present on thecentrifuge assembly 14 and/or the blood separation chamber 22.Alternatively, rather than intensity-based information, the opticalsensor system 70 may be configured to gather spectrally-basedinformation, thereby acting as a spectrometer. For example, whenemploying a white light source, different wavelengths of the lightpassing through the ramp 66 and fluid thereon will be absorbed by thedifferent types of fluid that may appear on the ramp 66. The light thatis reflected to a scanning fiber 90 a-90 c may be passed through aspectral beam splitter and then to a pair of light detectors 88 a, witheach detector receiving the unique wavelengths passed thereto andgenerating signals based on that data. The signals may be passed to acontroller or processing module that considers the individual signals(e.g., considering red vs. blue light absorption) and/or compares themto historical signals (e.g., considering the difference in blue lightabsorption over time) to generate information about the fluid in theblood separation chamber 22 (e.g., lipid concentration, the presence ofcellular blood components in separated plasma, platelet concentration,and hemolysis) and/or to cause adjustments in the operation of thesystem 10.

Furthermore, the optical sensor system 70 may include additional oralternative components without departing from the scope of the presentdisclosure. For example, FIG. 15 shows one or more power or statusindicators 132 (which can be a visual indicator that the optical sensorsystem 70 is functional) and one or more voltage regulators 134associated with the indicators 132, the driver 100, and variousamplifiers 124. The system may also include various connectors 136between the various components (e.g., BNC connectors, 3-pin connectorsto a power source, etc.), as well as to other components that are notillustrated. In other embodiments, a non-white, non-LED light sourceand/or non-photodiode light detectors (e.g., a camera sensor or an areasensor array or a linear sensor array) may be employed and/or otherillustrated components may be replaced with non-illustrated componentssuited to perform a similar or comparable function.

D. Alternative Centrifuge Yokes

As described above, centrifuge assemblies according to the presentdisclosure may be provided as umbilicus-driven (as illustrated in FIGS.1 and 2) or as direct-driven. If the centrifuge assembly isumbilicus-driven, additional steps may be taken to reduce the risk ofthe view of the ramp 66 by the optical sensor system 70 being blocked orobscured by the yoke 20 or umbilicus 38 during use.

According to one approach, a centrifuge assembly 14 a having a modifiedyoke 20 a is provided, as shown in FIGS. 17-19. The yoke 20 a includesfirst and second support arms 200 and 202, which are shown as beinggenerally diametrically opposed, with the centrifuge bowl 16 positionedtherebetween. The yoke 20 a is configured and operates generallyaccording to the above description of the yoke 20 of FIGS. 1 and 2, withthe exception that one of the support arms (illustrated as secondsupport arm 202) defines an opening or aperture or window 204therethrough. As will be described in greater detail, the yoke window204 is configured to provide a sight line through the support arm 202 toallow the optical sensor system 70 to view and monitor the ramp 66.Accordingly, the yoke window 204 is preferably significantly larger thanthe ramp 66 to maximize the visibility of the ramp 66 through thesupport arm 202, with a height H (the vertical dimension in theorientation of FIG. 17) that is greater than the height of the ramp 66(shown in FIG. 17 as a pair of broken lines 206 to represent themultiple possible positions of the ramp 66 as the centrifuge bowl 16 isrotated) and a width or angular extent W (FIG. 19) that is greater thanthe width or angular extent of the ramp 66. Preferably, the yoke window204 is positioned with the ramp 66 centered along the height H of theyoke window 204 (i.e., with the vertical center of the ramp 66 being atthe same elevation as the vertical center of the yoke window 204 in theorientation of FIG. 17), but it is also within the scope of the presentdisclosure for the ramp 66 to be closer to the top or bottom of the yokewindow 204.

Increasing the width or angular extent W of the yoke window 204increases the visibility of the ramp 66 by the optical sensor system 70.As best shown in FIGS. 18 and 19, the yoke window 204 preferably has awidth or angular extent W equal to or greater than that of the opposingsupport arm 200 at the same elevation, with the other support arm 200being diametrically opposed to the yoke window 204. By such aconfiguration, there is never one visual obstruction or obstacle (e.g.,one of the support arms 200, 202) positioned 180° from another visualobstruction or obstacle (e.g., the other support arm). By way ofexample, FIG. 18 shows opposing first and second sight lines 208 and 210into the centrifuge bowl 16 from a position outside of the centrifugeassembly 14 a (e.g., from the position of the optical sensor system 70).When the first sight line 208 is blocked by the first support arm 200(FIG. 18), there is visibility into the centrifuge bowl 16 180° awayalong the second sight line 208 via the yoke window 204. When the secondsight line 210 is blocked by the second support arm 202 (FIG. 19), thereis visibility into the centrifuge bowl 16 180° away along the firstsight line 200 to the side of the first support arm 200.

The illustrated configuration may be preferred because of the fact thatthe yoke 20 a rotates at one half the speed of the centrifuge bowl 16,as described above in greater detail. In such a rotational relationship,a 180° rotation of the yoke 20 a will result in a 360° rotation of thecentrifuge bowl 16. Thus, the ramp 66 will be at the same position(e.g., in position to be viewed by the optical sensor system 70) uponeach 180° rotation of the yoke 20 a. Accordingly, if the yoke isprovided with visual obstructions or obstacles positioned 180° apart,then it may be that the view of the ramp 66 will be obstructed duringconsecutive 360° rotations of the centrifuge bowl 16. In contrast, ifthe yoke is provided so as to eliminate any obstructions positioned 180°apart (as in the embodiment of FIGS. 17-19), then even if the view ofthe ramp 66 is obstructed at one time, the view of the ramp 66 by theoptical sensor system 70 will be clear during the next 360° rotation ofthe centrifuge bowl 16.

In connection with the yoke 20 a of FIGS. 17-19 (or providedseparately), the optical sensor system 70 may include a component thatcan distinguish between an obstructed or partially obstructed view andan unobstructed view. This functionality may be incorporated one of theexisting components (e.g., the interface processing module 126) orinstead be provided by a separate component. In one embodiment, this isaccomplished by bracketing the time it takes to scan the ramp 66 twiceand comparing the pulse-widths of the two scans obtained during thattime period. A partially obstructed scan will have a shorter pulse-widththan an unobstructed scan, while a fully obstructed scan will have nopulse-width. By bracketing the time it takes to scan the ramp 66 twice,a fully obstructed scan with no pulse-width may be considered, whereassuch a scan may be ignored or missed if the distinguishing device onlydetects and measures non-zero pulse-widths. When one of the scans has agreater pulse-width than the other, the scan having the largerpulse-width may be selected for further processing and use in thecontrol system. If the pulse-widths of the scans are the same orapproximately the same, either one or both of the scans may be selectedfor further processing and use in the control system. It should beunderstood that this bracketing method is only one way of distinguishingbetween obstructed and unobstructed views of the ramp 66, and othermethods of distinguishing between obstructed and unobstructed views ofthe ramp 66 may be employed without departing from the scope of thepresent disclosure.

While FIGS. 17-19 illustrate a two-armed yoke 20 a, with one of thesupport arms 202 having a window 204 therethrough for improvedvisibility into the centrifuge bowl 16 from an externally locatedoptical sensor system, it is also within the scope of the presentdisclosure to omit one of the support arms. For example, FIG. 20 showsonly one support arm 302 of a yoke 20 b. If the yoke 20 b includes onlyone support arm 302, then the above-described concern of a visualobstruction located 180° away from the support arm 302 is effectivelyeliminated.

According to another aspect of the present disclosure that isillustrated in FIG. 20, a yoke 20 b having an optical fiber bundle 300associated therewith is provided. In the illustrated embodiment, anoptical fiber bundle 300 is secured to an exterior and/or an interiorportion one of the yoke support arms 302, but it is also within thescope of the present disclosure for a single optical fiber bundle to beassociated with two yoke support arms or for separate optical fiberbundles to be associated with each yoke support arm (if more than onesupport arm is provided). The optical fiber bundle 300 extends between afirst or lower end 304 and a second or upper end 306. The lower end 304is illustrated in greater detail in FIGS. 21 and 22, while the upper end306 is illustrated in greater detail in FIG. 23. The lower end 304 isoriented in light-receiving and light-transmitting relationship to anillumination and detection assembly or optical sensor system 308, whichwill be described in greater detail. The upper end 306 is directedtoward the centrifuge bowl 16 of the centrifuge assembly 14 b, inlight-receiving and light-transmitting relationship to the ramp 66 ofthe centrifuge bowl 16. There may be an air gap between the upper andlower ends of the optical fiber bundle 300 and the centrifuge bowl 16and illumination and detection assembly 308, respectively, therebyavoiding the need to use an optical slip ring or fiber optic rotaryjoint or the like.

The optical fiber bundle 300 includes one or more of signal fibers 310and one or more illumination fibers 312, all of which are configured totransmit light between the ends 304 and 306 of the optical fiber bundle300. In one embodiment, the signal fibers 310 are positioned at anddirectly adjacent to the central axis of the optical fiber bundle 300,while the illumination fibers 312 are positioned around the signalfibers 310, such as in a ring or annular arrangement. This configurationis advantageous when used in combination with the particularillumination and detection assembly 308 of FIG. 20, but other fiberconfigurations (such as the mixed arrangement of signal fibers 310 andillumination fibers 312 shown in FIG. 23A or a configuration thatpositions the illumination fibers 312 at and directly adjacent to thecentral axis of the optical fiber bundle 300, with the signal fibers 310positioned around the illumination fibers 312) may be employed withdifferently configured illumination and light detection assemblies.

The illumination and detection assembly 308 of FIG. 20 includes at leastone light detector 314 and at least one light source 316. Theillustrated light detector(s) 314 and the light source(s) 316 areconfigured to correspond generally to the locations of the signal fibers310 and illumination fibers 312, respectively. In particular, theillustrated illumination and detection assembly 308 comprises a centralphotodiode 314 or other suitable light detector aligned with the centralaxis of the optical fiber bundle 300 at its lower end 304 (to correspondto the location of the signal fibers 310 at and directly adjacent to thecentral axis of the optical fiber bundle 300) and a plurality oflight-emitting diodes or laser diodes 316 or other suitable lightsources arranged in a ring around the light detector 314 (to correspondto the location of the illumination fibers 312 at the lower end 304 ofthe optical fiber bundle 300). The light source(s) 316 may be spacedaway from the light detector(s) 314 to prevent the light detector(s) 314from receiving light from the light source(s) 316, in which case thelower end 304 of the optical fiber bundle 304 may be outwardly flared(FIGS. 21 and 22) to similarly separate the signal fibers 310 from theillumination fibers 310 and to maintain the fibers in properregistration with the associated components of the illumination anddetection assembly 308.

In use, light is emitted by the light source(s) 316 in a directionsubstantially parallel to the rotational axis and received by theillumination fibers 310 at the lower end 304 of the optical fiber bundle300. The illumination fibers 310 transmit the light to the upper end 306of the optical fiber bundle 300, where it is directed onto the outersurface of the centrifuge bowl 16 in a generally radial direction,including the ramp 66 when it has rotated into light-receivingrelationship with the upper end 306 of the optical fiber bundle 300. Thelight source(s) 316 may be configured to be always on or to only be onwhen the ramp 66 is in light-receiving relationship with the upper end306 of the optical fiber bundle 300. Light from the illumination fibers312 passes through the ramp 66 and the fluid thereon (as described abovewith respect to the embodiment of FIGS. 1-16). The light is reflectedback through the ramp 66 and out of the centrifuge bowl 16 (by aretroreflector or mirror or the like, as described above with respect tothe embodiment of FIGS. 1-16), where it is received by the signal fibers310 at the upper end 306 of the optical fiber bundle 300. The signalfibers 310 transmit the reflected light from the upper end 306 of theoptical fiber bundle 300 to the lower end 304 of the optical fiberbundle 300, where it is directed toward the light detector(s) 314. Thelight detector(s) 314 receives the light from the signal fibers 310 andtransmits the data to a processor, such as the interface command module126, for detecting and controlling the location of the interface on theramp 66 and/or determining other information about the fluid on the ramp66.

According to one embodiment, a wide variety of information may bedetermined about the fluid processing region by providing two or morelight sources 316 configured to emit light having differing wavelengths.The light sources 316 may operate simultaneously or be controlled tofunction separately (e.g, by switching selected light sources 316 onduring one sampling session or rotation of the centrifuge bowl 16 andthe switching those light sources 316 off and other light sources 316 onduring another sampling session or rotation of the centrifuge bowl 16)to direct light of differing wavelengths into the fluid processingregion, which different wavelengths may be used to determine differentinformation about the fluid processing region (e.g., lipemia orhemolysis or the location of the interface, etc.).

In the illustrated embodiment, the light detector(s) 314 and the lightsource(s) 316 are all positioned at the same general location, which maybe at a non-rotating surface of the centrifuge assembly 14 b along theaxis of rotation, but it is also within the scope of the presentdisclosure for the components to be located at different locations. Itis also within the scope of the present disclosure for the illuminationand signal fibers to be positioned at different locations. For example,the illumination fibers 312 may be positioned as shown in FIG. 20, whilethe signal fibers 310 are at least partially positioned within thecentrifuge bowl 16 to directly receive light from the illuminationfibers 312 after it has passed through the ramp 66 (e.g., with the upperends of the signal fibers 301 being located on the centrifuge spoolbehind the ramp 66, where the retroreflector or mirror would otherwisebe to receive light transmitted through the ramp 66). The signal fibers310 would then transmit the light from the illumination fibers 312 tothe light detector 314, wherever it may be located.

Optical sensor systems of the type illustrated in FIG. 20 have severaladvantages. For example, such a design takes advantage of the proximityof the optical fiber to the fluid processing region to implement anon-imaging light collection system. This allows for more generousalignment and focusing tolerances and illumination requirements incomparison to other known optical sensor systems. Additionally, onaccount of the light being directed into the fluid processing regionfrom a position that rotates in the same direction as the fluidprocessing region, the signal received from the fluid processing regionmay be longer than a signal resulting from light directed into the fluidprocessing region from a stationary position (e.g., on the order oftwice the duration).

Systems of the type illustrated in FIG. 20 may be used alone or incombination with the other aspects described herein. For example, thesystem of FIG. 20 may be used in combination with the optical sensorsystem 70 to act as an auxiliary optical sensor system in the event thatthe view of the optical sensor system 70 becomes obscured or obstructedor to monitor a different aspect of the fluid on the ramp 66.

Aspects of the present subject matter described above may be beneficialalone or in combination with one or more other aspects. Without limitingthe foregoing description, in accordance with one aspect of the subjectmatter herein, there is provided a blood processing system whichincludes a centrifuge assembly having a light-transmissive portion, alight reflector, and a fluid processing region at least partiallypositioned between the light-transmissive portion and the lightreflector. The blood processing system also includes an optical sensorsystem configured to emit a scanning light beam along a path toward thelight-transmissive portion of the centrifuge assembly. Thelight-transmissive portion of the centrifuge is configured to transmitat least a portion of the scanning light beam to the fluid processingregion and the light reflector. The light reflector is configured toreflect at least a portion of the scanning light beam toward the opticalsensor system along a path substantially coaxial to the path of thescanning light beam from the optical sensor system toward thelight-transmissive portion of the centrifuge assembly.

In accordance with another aspect which may be used or combined with thepreceding aspect, the path of the scanning light beam from the opticalsensor system toward the light-transmissive portion of the centrifugeassembly is substantially parallel to a radius passing through therotational axis of the centrifuge assembly. However, the path of thescanning light beam from the optical sensor system toward thelight-transmissive portion of the centrifuge assembly is oriented so asnot to pass through the rotational axis of the centrifuge assembly.

In accordance with another aspect which may be used or combined with anyof the preceding aspects, the light reflector is a retroreflector.

In accordance with another aspect which may be used or combined with anyof the preceding aspects, the optical sensor system also includes afirst light detector, a source light configured to emit a source lightbeam, and a beam splitter. The beam splitter is configured to receiveand split the source light beam into the scanning light beam and areference light beam. The beam splitter also directs the scanning lightbeam toward the light-transmissive portion of the centrifuge assemblyand directs the reference light beam toward the first light detector.

In accordance with another aspect which may be used or combined with thepreceding aspect, the beam splitter is configured to direct the scanninglight beam and the reference light beam in substantially perpendiculardirections.

In accordance with another aspect which may be used or combined with anyof the preceding two aspects, the optical sensor system further includesa second light detector. The beam splitter is configured to direct thereflected scanning light beam toward the second light detector.

In accordance with another aspect which may be used or combined with thepreceding aspect, the beam splitter is configured to direct thereflected scanning light beam in a direction substantially perpendicularto the path of the scanning light beam from the light reflector towardthe optical sensor system.

In accordance with another aspect which may be used or combined with anyof the preceding four aspects, the optical sensor system furtherincludes a controller associated with the first light detector and thesource light and configured to adjust the brightness of the source lightbeam based at least in part on a characteristic of the reference lightbeam.

In accordance with another aspect which may be used or combined with anyof the preceding aspects, the system is configured to determine thelocation of an interface between separated blood components in thecentrifuge assembly.

In accordance with another aspect, there is provided a method formonitoring fluid within a blood processing system having a centrifugeassembly. The method includes separating blood in a centrifuge assemblyinto at least two blood components and directing a scanning light beamalong a path toward and into the centrifuge assembly so as to intersectthe blood or at least one of the blood components. At least a portion ofthe scanning light beam is reflected after intersecting the blood orblood component, with the reflected light being directed along a pathout of the centrifuge assembly that is substantially coaxial to the pathof the scanning light beam toward and into the centrifuge assembly. Atleast a portion of the reflected light is received and analyzed.

In accordance with another aspect which may be used or combined with thepreceding aspect, the scanning light beam is directed in a directionthat is substantially parallel to a radius passing through therotational axis of the centrifuge assembly, but that does not passthrough the rotational axis of the centrifuge assembly.

In accordance with another aspect which may be used or combined with anyof the preceding two aspects, at least a portion of the scanning lightbeam is reflected with a retroreflector.

In accordance with another aspect which may be used or combined with anyof the preceding three aspects, the reflected portion of the scanninglight beam is directed in a direction substantially perpendicular to thepath of the scanning light beam toward and into the centrifuge assemblyprior to being received and analyzed.

In accordance with another aspect which may be used or combined with anyof the preceding three aspects, a source light beam is split into thescanning light beam and reference light beam, with the reference lightbeam being directed toward a light detector substantially simultaneouslywith the scanning light beam being directed toward and into thecentrifuge assembly.

In accordance with another aspect which may be used or combined with thepreceding aspect, the scanning light beam and the reference light beamare directed in substantially perpendicular directions.

In accordance with another aspect which may be used or combined with anyof the preceding two aspects, at least a portion of the reference lightbeam is received and analyzed, with the brightness of the source lightbeam being adjusted based at least in part on a characteristic of thereference light beam.

In accordance with another aspect which may be used or combined with anyof the preceding seven aspects, the reflected light is analyzed todetermine the location of an interface between separated bloodcomponents in the centrifuge assembly.

In accordance with another aspect, there is provided an optical sensorsystem for use in combination with a blood processing system. Theoptical sensor system includes a light source, a light detector, and anoptical fiber providing a light path between the light source and thelight detector.

In accordance with another aspect which may be used or combined with thepreceding aspect, the light source is at least partially positionedwithin a housing, the light detector is positioned outside of thehousing, and the optical fiber is connected to the housing.

In accordance with another aspect which may be used or combined with thepreceding aspect, the optical fiber is adjustably connected to thehousing.

In accordance with another aspect which may be used or combined with thepreceding aspect, a plurality of optical fibers are connected to thehousing by an adjustable module configured to simultaneously adjust theposition of the optical fibers with respect to the housing.

In accordance with another aspect which may be used or combined with anyof the preceding four aspects, a beam splitter is configured to receivelight from the light source and direct at least a portion of the lighttoward the optical fiber.

In accordance with another aspect which may be used or combined with thepreceding aspect, the beam splitter is configured to receive light fromthe light source and direct portions of the light toward a plurality ofoptical fibers in different directions.

In accordance with another aspect which may be used or combined with thepreceding aspect, the beam splitter is configured to direct the portionsof the light in opposite directions toward the optical fibers.

In accordance with another aspect which may be used or combined with anyof the preceding seven aspects, the optical fiber is oriented at anangle with respect to the direction of a light beam emitted by the lightsource.

In accordance with another aspect which may be used or combined with anyof the preceding eight aspects, the optical fiber is orientedsubstantially perpendicular to the direction of a light beam emitted bythe light source.

In accordance with another aspect, there is provided a blood processingsystem which includes a centrifuge assembly having a light-transmissiveportion, a light reflector, and a fluid processing region at leastpartially positioned between the light-transmissive portion and thelight reflector. The blood processing system also includes an opticalsensor system having a light source configured to emit a source lightbeam, a light detector, and an optical fiber providing a light path tothe light detector. The light-transmissive portion of the centrifugeassembly is configured to transmit at least a portion of the sourcelight beam to the fluid processing region and the light reflector. Thelight reflector is configured to reflect at least a portion of thesource light beam toward the optical sensor assembly. The optical fiberis configured to conduct at least a portion of the reflected sourcelight beam toward the light detector.

In accordance with another aspect which may be used or combined with thepreceding aspect, the light source is at least partially positionedwithin a housing, the light detector is positioned outside of thehousing, and the optical fiber is connected to the housing.

In accordance with another aspect which may be used or combined with thepreceding aspect, the optical fiber is adjustable connected to thehousing.

In accordance with another aspect which may be used or combined with thetwenty-eighth aspect, a plurality of optical fibers connected to thehousing by an adjustable module configured to simultaneously adjust theposition of the optical fibers with respect to the housing.

In accordance with another aspect which may be used or combined with anyof the preceding four aspects, a beam splitter is configured to receivethe source light beam and direct at least a portion of the source lightbeam toward the optical fiber.

In accordance with another aspect which may be used or combined with thepreceding aspect, the beam splitter is configured to direct a portion ofthe source light beam in a direction toward the optical fiber and toreceive and direct at least a portion of the reflected source light beamtoward another optical fiber in a different direction.

In accordance with another aspect which may be used or combined with thepreceding aspect, the lights are directed toward the optical fibers inopposite directions.

In accordance with another aspect which may be used or combined with anyof the preceding seven aspects, the optical fiber is oriented at anangle with respect to the direction of the source light beam.

In accordance with another aspect which may be used or combined with anyof the preceding eight aspects, the optical fiber is orientedsubstantially perpendicular to the direction of the source light beam.

In accordance with another aspect, there is provided a method formonitoring fluid within a blood processing system having a centrifugeassembly. The method includes separating blood in a centrifuge assemblyinto at least two blood components and generating a source light beam.At least a portion of the source light beam is directed into thecentrifuge assembly so as to intersect the blood or at least one of theblood components. At least a portion of the source light beam isreflected after intersecting the blood or blood component and is thendirected toward a light detector through an optical fiber.

In accordance with another aspect which may be used or combined with thepreceding aspect, at least one characteristic of the reflected sourcelight beam is detected using the light detector and a characteristic ofthe blood or at least one of the blood components is determined based,at least in part, on a characteristic of the reflected source lightbeam.

In accordance with another aspect which may be used or combined with anyof the preceding two aspects, the reflected source light beam isdirected along a path substantially perpendicular to the direction ofthe reflected source light beam.

In accordance with another aspect which may be used or combined with anyof the preceding three aspects, at least a portion of the source lightbeam is directed toward a second light detector through a second opticalfiber.

In accordance with another aspect which may be used or combined with anyof the preceding four aspects, the optical fiber is oriented at an anglewith respect to the direction of the source light beam.

In accordance with another aspect which may be used or combined with anyof the preceding five aspects, the optical fiber is orientedsubstantially perpendicular to the direction of the source light beam.

In accordance with another aspect, there is provided an optical sensorsystem for use in combination with a blood processing system. Theoptical sensor system includes a white light source.

In accordance with another aspect which may be used or combined with thepreceding aspect, the white light source is a light-emitting diode.

In accordance with another aspect which may be used or combined with anyof the preceding two aspects, the white light source has a relativelyhigh spectral power distribution in the red wavelength spectrum.

In accordance with another aspect which may be used or combined with anyof the preceding three aspects, the white light source has a relativelyhigh spectral power distribution in the blue wavelength spectrum.

In accordance with another aspect which may be used or combined with anyof the preceding four aspects, a light detector is positioned adjacentto the white light source and configured to monitor the intensity oflight emitted by the white light source.

In accordance with another aspect, there is provided a blood processingsystem including a centrifuge assembly and an optical sensor system. Thecentrifuge assembly includes a light-transmissive portion and a fluidprocessing region positioned at least partially adjacent to thelight-transmissive portion. The optical sensor system emits a whitelight directed toward the light-transmissive portion of the centrifugeassembly.

In accordance with another aspect which may be used or combined with thepreceding aspect, the optical sensor system includes a white lightsource comprising a light-emitting diode.

In accordance with another aspect which may be used or combined with thepreceding aspect, the white light source has a relatively high spectralpower distribution in the red wavelength spectrum.

In accordance with another aspect which may be used or combined with anyof the preceding two aspects, the white light source has a relativelyhigh spectral power distribution in the blue wavelength spectrum.

In accordance with another aspect which may be used or combined with anyof the preceding three aspects, a light detector is positioned adjacentto the white light source and configured to monitor the intensity oflight emitted by the white light source.

According to another aspect, there is provided a method for monitoringfluid within a blood processing system having a centrifuge assembly. Themethod includes separating blood in a centrifuge assembly into at leasttwo blood components and generating a source light beam comprising awhite light. At least a portion of the source light beam is directedtoward and into the centrifuge assembly so as to intersect the blood orat least one of the blood components. At least a portion of the sourcelight beam is reflected after intersecting the blood or blood componentand at least one characteristic of the reflected source light beam isdetected.

In accordance with another aspect which may be used or combined with thepreceding aspect, a characteristic of the blood or at least one of theblood components is determined based, at least in part, on acharacteristic of the reflected source light beam.

In accordance with another aspect which may be used or combined with anyof the preceding two aspects, the intensity of the source light beam ismonitored from a location adjacent to the source of the source lightbeam.

In accordance with another aspect, there is provided a blood processingsystem which includes a centrifuge assembly having a light-transmissiveportion, a light reflector, and a fluid processing region at leastpartially positioned between the light-transmissive portion and thelight reflector. The blood processing system also includes an opticalsensor system having a light source configured to emit a source lightbeam and a plurality of light detectors. The light-transmissive portionof the centrifuge assembly is configured to transmit at least a portionof the source light beam to the fluid processing region and the lightreflector. The light reflector is configured to reflect at least aportion of the source light beam toward the optical sensor system. Theplurality of light detectors are configured to detect at least onecharacteristic of the reflected source light beam at differentlocations.

In accordance with another aspect which may be used or combined with thepreceding aspect, a plurality of optical fibers are configured toreceive different portions of the reflected source light beam and todirect the different portions of the reflected source light beam to thelight detectors.

In accordance with another aspect which may be used or combined with thepreceding aspect, an adjustable module is configured to simultaneouslyadjust the position of the optical fibers with respect to the reflectedsource light beam.

In accordance with another aspect which may be used or combined with anyof the preceding three aspects, the different locations are in the sameplane.

In accordance with another aspect which may be used or combined with anyof the preceding four aspects, the different locations are in a planeangled with respect to the rotational axis of the centrifuge assembly.

In accordance with another aspect, there is provided a method formonitoring fluid within a blood processing system having a centrifugeassembly. The method includes separating blood in a centrifuge assemblyinto at least two blood components and generating a source light beam.The source light beam is directed toward and into the centrifugeassembly so as to intersect the blood or at least one of the bloodcomponents. At least a portion of the source light beam is reflectedafter intersecting the blood or blood component and at least onecharacteristic of the reflected source light beam is detected at aplurality of different locations.

In accordance with another aspect which may be used or combined with thepreceding aspect, a characteristic of the blood or at least one of theblood components is determined based, at least in part, on acharacteristic of the reflected source light beam.

In accordance with another aspect which may be used or combined with anyof the preceding two aspects, the different locations at which thecharacteristic of the reflected source light beam is detected aresimultaneously adjusted.

In accordance with another aspect which may be used or combined with anyof the preceding three aspects, the plurality of different locations arein the same plane.

In accordance with another aspect which may be used or combined with anyof the preceding four aspects, the plurality of different locations arein a plane angled with respect to the rotational axis of the centrifugeassembly.

In accordance with another aspect, there is provided a blood processingsystem which includes a centrifuge assembly having a rotational axis.The blood processing system also includes an optical sensor systemhaving a light source that emits a source light beam directed along apath parallel to a radius passing through the rotational axis of thecentrifuge assembly. The path of the source light beam is oriented so asto not pass through the rotational axis of the centrifuge assembly.

In accordance with another aspect, there is provided a method formonitoring fluid within a blood processing system having a centrifugeassembly with a rotational axis. The method includes separating blood ina centrifuge assembly into at least two blood components and generatinga source light beam. At least a portion of the source light beam isdirected along a path parallel to a radius passing through therotational axis of the centrifuge assembly, but oriented so as to notpass through the rotational axis of the centrifuge assembly, and intothe centrifuge assembly so as to intersect the blood or at least one ofthe blood components. At least a portion of the source light beam isreflected after intersecting the blood or blood component and then atleast one characteristic of the reflected source light beam is detected.

In accordance with another aspect which may be used or combined with thepreceding aspect, a characteristic of the blood or at least one of theblood components is determined based, at least in part, on acharacteristic of the reflected source light beam.

In accordance with another aspect, there is provided a blood processingsystem which includes a centrifuge assembly having a rotational axis.The centrifuge assembly has a light-transmissive portion, a fluidprocessing region positioned radially inwardly of the light-transmissiveportion, and a yoke including a first support arm configured to rotatethe light-transmissive portion and the fluid processing region about therotational axis. The blood processing system also includes an opticalsensor system configured to direct a light toward the light-transmissiveportion of the centrifuge assembly. The yoke is positioned between thelight-transmissive portion and the optical sensor system and isconfigured to allow passage of at least a portion of the light throughthe first support arm as the light is directed toward thelight-transmissive portion.

In accordance with another aspect which may be used or combined with thepreceding aspect, the first support arm defines a window through whichlight from the optical sensor system may pass.

In accordance with another aspect which may be used or combined with anyof the preceding two aspects, the yoke includes a second support armpositioned opposite the first support arm.

In accordance with another aspect which may be used or combined with thepreceding aspect, the angular extent of the window is at least as greatas the angular extent of the second support arm.

In accordance with another aspect, there is provided a blood processingsystem which includes a centrifuge assembly having a rotational axis.The centrifuge assembly has a light-transmissive portion, a fluidprocessing region positioned radially inwardly of the light-transmissiveportion, and a yoke. The yoke includes a first support arm configured torotate the light-transmissive portion and the fluid processing regionabout the rotational axis. An optical fiber bundle extends between firstand second ends and is associated with the support arm of the yoke. Theblood processing system also includes an optical sensor systemconfigured to direct a light toward the first end of the optical fiberbundle. The second end of the optical fiber bundle directs the lighttoward the light-transmissive portion.

In accordance with another aspect which may be used or combined with thepreceding aspect, the optical sensor system is configured to direct thelight in a direction substantially parallel to the rotational axis.

In accordance with another aspect which may be used or combined with anyof the preceding two aspects, the second end of the optical fiber bundleis configured to direct the light in a generally radial direction.

In accordance with another aspect which may be used or combined with anyof the preceding three aspects, the first end of the optical fiberbundle has a greater outer diameter than the second end.

In accordance with another aspect which may be used or combined with anyof the preceding four aspects, a light reflector is associated with thelight-transmissive portion. At least a portion of the light directedtoward the light-transmissive portion is directed to the optical fiberbundle by the light reflector. The optical fiber bundle is configured todirect at least a portion of the reflected light toward the opticalsensor system.

In accordance with another aspect which may be used or combined with thepreceding aspect, the optical fiber bundle includes at least one signalfiber configured to direct reflected light from the light reflectortoward the optical sensor system and a plurality of illumination fibersconfigured to direct light from the optical sensor system toward thelight-transmissive portion. The at least one signal fiber is positioneddirectly adjacent to a central axis of the optical fiber bundle and theillumination fibers are positioned radially outwardly of the at leastone signal fiber.

It will be understood that the embodiments described above areillustrative of some of the applications of the principles of thepresent subject matter. Numerous modifications may be made by thoseskilled in the art without departing from the spirit and scope of theclaimed subject matter, including those combinations of features thatare individually disclosed or claimed herein. For these reasons, thescope hereof is not limited to the above description but is as set forthin the following claims, and it is understood that claims may bedirected to the features hereof, including as combinations of featuresthat are individually disclosed or claimed herein.

The invention claimed is:
 1. A blood processing system, comprising: acentrifuge assembly having a rotational axis and including alight-transmissive portion, a light reflector, and a fluid processingregion at least partially positioned between the light-transmissiveportion and the light reflector; and an optical sensor system configuredto emit a scanning light beam along a path toward the light-transmissiveportion of the centrifuge assembly that is substantially parallel to aradius passing through the rotational axis of the centrifuge assembly,but which path does not pass through the rotational axis of thecentrifuge assembly, wherein the light-transmissive portion of thecentrifuge assembly is configured to transmit at least a portion of thescanning light beam to the fluid processing region and the lightreflector, and the light reflector is configured to reflect at least aportion of the scanning light beam toward the optical sensor systemalong a path substantially coaxial to the path of the scanning lightbeam from the optical sensor system toward the light-transmissiveportion of the centrifuge assembly.
 2. The blood processing system ofclaim 1, wherein the light reflector comprises a retroreflector.
 3. Theblood processing system of claim 1, wherein the optical sensor systemfurther includes a first light detector, a source light configured toemit a source light beam, and a beam splitter configured to receive andsplit the source light beam into said scanning light beam and areference light beam, direct the scanning light beam toward thelight-transmissive portion of the centrifuge assembly, and direct thereference light beam toward the first light detector.
 4. The bloodprocessing system of claim 3, wherein the beam splitter is configured todirect the scanning light beam and the reference light beam insubstantially perpendicular directions.
 5. The blood processing systemof claim 3, wherein the optical sensor system further includes a secondlight detector, and the beam splitter is configured to direct thereflected scanning light beam toward the second light detector.
 6. Theblood processing system of claim 5, wherein the beam splitter isconfigured to direct the reflected scanning light beam in a directionsubstantially perpendicular to the path of the scanning light beam fromthe light reflector toward the optical sensor system.
 7. The bloodprocessing system of claim 3, wherein the optical sensor system furtherincludes a controller associated with the first light detector and thesource light and configured to adjust the brightness of the source lightbeam based at least in part on a characteristic of the reference lightbeam.
 8. The blood processing system of claim 1, wherein the system isconfigured to determine the location of an interface between separatedblood components in the centrifuge assembly.
 9. The blood processingsystem of claim 1, wherein the optical sensor system includes a lightsource; a light detector; and an optical fiber providing a light pathbetween the light source and the light detector.
 10. The bloodprocessing system of claim 1, wherein the optical sensor system includesa white light source.
 11. The blood processing system of claim 1,wherein the optical sensor system includes a plurality of lightdetectors configured to detect at least one characteristic of thereflected scanning light beam at different locations.
 12. The bloodprocessing system of claim 1, wherein the light transmissive portion ofthe centrifuge assembly is incorporated into a bowl having asubstantially circular perimeter, the centrifuge assembly includes aramp associated with the bowl and at least partially aligned with thelight-transmissive portion, and the ramp defines a prism includingangled inner and outer faces that are non-tangential to the perimeter ofthe bowl.
 13. The blood processing system of claim 12, wherein there isan angle of approximately 55.4° between the inner and outer faces of theprism.
 14. The blood processing system of claim 1, wherein thecentrifuge assembly includes a ramp associated with thelight-transmissive portion, and the ramp is oriented to receive thescanning light beam at a position rotated approximately 10° from aradius passing through the rotational axis of the centrifuge assemblyand parallel to the path of the scanning light beam from the opticalsensor system toward the light-transmissive portion.
 15. A method ofmonitoring fluid within a blood processing system having a centrifugeassembly with a rotational axis, the method comprising: separating bloodin a centrifuge assembly into at least two blood components; directing ascanning light beam along a path toward and into the centrifuge assemblyso as to intersect the blood or at least one of the blood components,wherein said path is substantially parallel to a radius passing throughthe rotational axis of the centrifuge assembly, but which path does notpass through the rotational axis of the centrifuge assembly; reflectingat least a portion of the scanning light beam after intersecting theblood or at least one of the blood components, thereby directing thereflected portion of the scanning light beam along a path out of thecentrifuge assembly that is substantially coaxial to the path of thescanning light beam toward and into the centrifuge assembly; andreceiving and analyzing at least a portion of the reflected portion ofthe scanning light beam.
 16. The method of claim 15, wherein saidreflecting at least a portion of the scanning light beam includesreflecting at least a portion of the scanning light beam with aretroreflector.
 17. The method of claim 15, wherein the reflectedportion of the scanning light beam is directed in a directionsubstantially perpendicular to the path of the scanning light beamtoward and into the centrifuge assembly prior to said receiving andanalyzing at least a portion of the reflected portion of the scanninglight beam.
 18. The method of claim 15, further comprising splitting asource light beam into said scanning light beam and a reference lightbeam prior to said directing a scanning light beam, and directing thereference light beam toward a light detector substantiallysimultaneously with said directing a scanning light beam.
 19. The methodof claim 18, wherein the scanning light beam and the reference lightbeam are directed in substantially perpendicular directions.
 20. Themethod of claim 18, further comprising receiving and analyzing at leasta portion of the reference light beam and adjusting the brightness ofthe source light beam based at least in part on a characteristic of thereference light beam.
 21. The method of claim 15, wherein said receivingand analyzing at least a portion of the reflected portion of thescanning light beam includes determining the location of an interfacebetween separated blood components in the centrifuge assembly.
 22. Ablood processing system, comprising: a centrifuge assembly having arotational axis and including a light-transmissive portion, a fluidprocessing region positioned radially inwardly of the light-transmissiveportion, and a yoke including a first support arm configured to rotatethe light-transmissive portion and the fluid processing region about therotational axis; and an optical sensor system configured to direct alight toward the light-transmissive portion, wherein the yoke ispositioned between the light-transmissive portion and the optical sensorsystem and the first support arm defines an aperture configured to allowpassage of at least a portion of the light through the first support armas the light is directed toward the light-transmissive portion when thefirst support arm is positioned between the light-transmissive portionand the optical sensor system.
 23. The blood processing system of claim22, wherein the centrifuge assembly includes a light reflector, thefluid processing region is at least partially positioned between thelight-transmissive portion and the light reflector, thelight-transmissive portion of the centrifuge assembly is configured totransmit at least a portion of the light to the light reflector, and thelight reflector is configured to reflect at least a portion of the lighttoward the optical sensor system along a path substantially coaxial tothe path of the light from the optical sensor system toward thelight-transmissive portion of the centrifuge assembly.
 24. A bloodprocessing system, comprising: a centrifuge assembly having a rotationalaxis and including a light-transmissive portion, a fluid processingregion positioned radially inwardly of the light-transmissive portion,and a yoke including a support arm configured to rotate thelight-transmissive portion and the fluid processing region about therotational axis, and an optical fiber bundle extending between first andsecond ends and associated with the support arm; and an optical sensorsystem is configured to direct a light toward the first end of theoptical fiber bundle, wherein the first end of the optical fiber bundleis oriented substantially coaxially with the rotational axis, and thesecond end of the optical fiber bundle directs the scanning light beamtoward the light-transmissive portion.
 25. The blood processing systemof claim 24, wherein the centrifuge assembly includes a light reflector,the fluid processing region is at least partially positioned between thelight-transmissive portion and the light reflector, thelight-transmissive portion of the centrifuge assembly is configured totransmit at least a portion of the light to the light reflector, and thelight reflector is configured to reflect at least a portion of the lighttoward the optical sensor system along a path substantially coaxial tothe path of the light from the optical sensor system toward thelight-transmissive portion of the centrifuge assembly.
 26. A bloodprocessing system, comprising: a centrifuge assembly having a rotationalaxis and including a light-transmissive portion, a light reflector, anda fluid processing region at least partially positioned between thelight-transmissive portion and the light reflector; and an opticalsensor system comprising a light detector, a source light configured toemit a source light beam, and a beam splitter configured to receive andsplit the source light beam into a scanning light beam and a referencelight beam, direct the scanning light beam toward the light-transmissiveportion of the centrifuge assembly, and direct the reference light beamtoward the light detector, wherein the light-transmissive portion of thecentrifuge assembly is configured to transmit at least a portion of thescanning light beam to the fluid processing region and the lightreflector, the light reflector is configured to reflect at least aportion of the scanning light beam toward the optical sensor systemalong a path substantially coaxial to the path of the scanning lightbeam from the optical sensor system toward the light-transmissiveportion of the centrifuge assembly, and said at least a portion of thescanning light beam reflected from the light reflector toward theoptical sensor system is wirelessly transmitted from the light reflectorto the beam splitter.
 27. A blood processing system, comprising: acentrifuge assembly having a rotational axis and including alight-transmissive portion, a light reflector, and a fluid processingregion at least partially positioned between the light-transmissiveportion and the light reflector; and an optical sensor system configuredto emit a light along a path toward the light-transmissive portion andincluding a plurality of light detectors, wherein the light-transmissiveportion is configured to transmit at least a portion of the light to thefluid processing region and the light reflector, the light reflector isconfigured to reflect at least a portion of the light toward the opticalsensor system as a single beam, and the plurality of light detectors areconfigured and oriented to simultaneously detect at least onecharacteristic of the single beam at different locations in a planeperpendicular to the path of the single beam, and detect a change insaid at least one characteristic of the single beam of reflected lightat different times in said different locations.